Attorneys for a teenage boy in Pennsylvania accused of beating his older brother to death with a hammer said they may present a "mental infirmity" defense. Prosecutors say Ian A. Bishop, 15, killed Adam Bishop, 18, on April 19 at their Westmoreland County home because he believed his brother was gay. Bishop's attorneys said they plan to present evidence that Bishop wasn't able to form the specific intent to kill, which is required for a first-degree murder conviction. The attorneys may offer evidence that Bishop suffers from "emergent antisocial, negativistic personality traits with self-defeating, borderline, and depressive features" that prompted the attack.

District Attorney John W. Peck dismissed the idea of a possible insanity defense. "We don't think he was in any kind of an impaired state," he said. The trial has not yet been scheduled.